Terms of Service Agreement by kfp17794

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									GRAAP:
Why do we need
SLAs?
Omer Rana
o.f.rana@cs.cardiff.ac.uk

                            1
GRAAP WG
    Current focus:
        WS-Agreement   specification
        Support for negotiation being investigated


    Investigating:
        Interoperability     (and conformance) issues
        Use          cases

      Longer term:
        Aspects  of “dynamic” SLAs
        Investigation of penalty/reward clauses



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What is a Service Level Agreement (SLA)?
        A relationship between a client and provider in the context of a particular
        capability (service) provision

                       Client                                Provider

                                         Can you
                                         do X for me
                                         for Y in
                      SLA                return?                    SLA

                                 SLA-Offer


                                         Yes
                                                       SLA-Accept
                                                       SLA-Reject


       Distinguish between: Discovery of suitable provider                P2P Search,
                            Establishment of an SLA                       Directory
                                                                          Service
OGF21, October 2007                                                                   3
What is an SLA?


                       Client                       Provider

                                Can you
                                do X for me
                                for Y in
                      SLA       return?                    SLA

                                SLA-Offer

                                  No, but I      SLA-CounterOffer
                                  can do Z
                                  for Y


                                              SLA-Accept
                                              SLA-Reject
                                   Accept
OGF21, October 2007                                                 4
What is an SLA?


                       Client                                       Provider

                                              Can you
                                              do X for me
                                              for Y in
                      SLA                     return?                    SLA

                                              SLA-Offer

                                                No
                                                            SLA-CounterOffer

                                                                           Negotiation
Dependency                                      SLA-Offer                  Phase
                                                                           (Single or
                                Can you
                                do Z for me
                                                                           Multi-Round)
                                for Y in
OGF21, October 2007
                                return?                                                   5
 Variations
                                                                         Providers
                               Providers
                                           Client
Client

                       SLA
                                                SLA         SLA




 Multi-provider SLA                           SLA dependencies

 Single SLA is divided                        For an SLA to be valid, another
 across multiple providers                    SLA has to be agreed
 (e.g. workflow composition)                  (e.g. co-allocation)


 OGF21, October 2007                                                            6
What is an SLA?
    Dynamically established and managed
     relationship between two parties
    Objective is “delivery of a service” by one of the
     parties in the context of the agreement
    Delivery involves:
        Functional       and non-functional properties of service
    Management of delivery:
        Roles,       rights and obligations of parties involved




OGF21, October 2007                                                  7
Forming the Agreement
    Distinguish between:
        Agreement itself
        Mechanisms that lead to the formation of the
         agreement


    Mechanisms that lead to agreement:
        Negotiation(single or multi-shot)
        One-shot creation
        Policy-based creation of agreements, etc.


OGF21, October 2007                                     8
SLA Life Cycle
    Identify Provider
        On           completion of a discovery phase
    Define SLA
        Define          what is being requested
    Agree on SLA terms
        Agree          on Service Level Objectives
    Monitor SLA Violation
        Confirm          whether SLO’s are being violated
    Destroy SLA
        Expire          SLA
    Penalty for SLA Violation

OGF21, October 2007                                          9
Why do we need SLAs?
    Provide some basis for:
           Judging “Quality” of provisioning
                     QoS can be provider or user related
           If “Violations” have occurred
                     Types of penalties
           Choosing providers/clients
           Capacity planning
           Scheduling
           Establishing trust/reputation
    OGF19 BoF: Difficulty in differentiating between QoS
     and SLAs
    OGF20: Dynamic SLA workshop
    Grid 2007 (Sept. 07): SLA Management for Grids (with
     CoreGrid – book from workshop will appear shortly)


OGF21, October 2007                                         10
WS-Agreement
 Framework for SLA creation – interface
  conforming to Web Services standards
 Service Client/Provider does not need to
  be a Web Service
 Provides a two layered model:
        Agreement    layer: Web Service-based
         interface to create, represent and monitor
         agreements
        Service layer: Application specific-layer of
         service being provided
OGF21, October 2007                                     11
WS-Agreement

                                                                        Agreement
                                                                        Layer




                                                                         Service
                                                                         Layer




      Agreement Initiator may be Service Consumer or Service Provider
OGF21, October 2007                                                        12
WS-Agreement
            Agreement
                                          Information about Agreement
                                          Initiator
Name/ID                                   Responder
                                          Expiration Time

Context
                                          Information about Service
                                          Service Description Terms
                                          (generally, these are domain
                                          dependent)

 Service Terms

                                            Information about Service
 Guarantee Terms                            Level
                                            Service Level Objectives,
                                            Qualifying Conditions for
                                            the agreement to be valid,
                      Terms Composition     Penalty Terms, etc


OGF21, October 2007                                                      13
WS-Agreement Terms




                      From: Viktor Yarmolenko (U Manchester)

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Usage
    A number of projects utilizing this
        Implementations   vary – two key
         implementations currently being developed
        Others utilizing part of the spec:
                Various European projects (CATNETs, SORMA,
                 OntoGrid)
                National projects (VIOLA)




OGF21, October 2007                                           15
CATNETS Scenario


                      Complex              Basic              Resource
                      Service             Service              Service

                      Complex              Basic              Resource
                      Service             Service              Service

                      Complex              Basic              Resource
                      Service             Service              Service


                                Service             Resource
                                Market               Market
            Service Consumer          Service Provider
                                     Resource Consumer   Resource Provider
OGF21, October 2007                                                      16
Service Market
                Demand:
                                                       Demand:
                Complex Database   (1)   Query         (8CPUs,1GB,30GB)
                Query                    Service       < 40 €
                < 200 €
                                   (2)
                                         Query
               Container 1 (40€)         Service
               Container 2 (50€)
               Container 3 (70€)
                                   (3)               Total Cost <
                                         Query       Cost of service +
                                         Service     Cost of resource


               Orderbook
               Complex Service       Basic Service



OGF21, October 2007                                                      17
Resource Market
                Demand:                     (4CPU,    [1,3] bundles
                                      (1)
                (8CPUs,1GB,30GB)              1GB,    allowed
                < 40 €                       15GB)

                                      (2)   (4CPU,
                                              1GB,
              Buy-Order 1 (10€)
                                             15GB)
              Buy-Order 2 (18€)
              Buy-Order 3 (35€)
                                      (3)   (8CPU,
                                              1GB,     Sum = 28 €
               Orderbook                     30GB)
               Basic Service 1


                           Ranking buy-orders        Build bundle



OGF21, October 2007                                                   18
CATNETs: Metrics “Pyramid”




OGF21, October 2007          19
Use of WS-Agreement
           1. Request


       Client           Application Service Builder
                                                                   8. Invocation

                                                                                                         ServiceInstance
                        Master Grid Service                              WS                              (GT4/JavaWS)
      2. Requirements
                                               7. Service
      Application            WSAG              Reference


                           Catallactic                                              5. Service
                          Access Point                3. Service                   instantiation
                                                     negotiation

                         ComplexService                     BasicService                           ServiceFactory
                            Agent                              Agent                               (GT4/JavaWS)

                                  6. Service                                 4. Resource
                                  Reference                                  negotiation

                                                            ResourceAgent
      CATNETS Middleware



                                                                   Resource (GT4/WSRF/.NETWS/JWS)
      Base Platform

CATNETS: U Bayreuth, U Karlsruhe, UPC/Barcelona, U Ancona, ITC/IRST (Trento), U Cardiff
                     EU FP6 “Future and Emerging Technologies”
Dynamic SLA
    Limitations of a single agreement
        Modifications         since agreement was in place
    Cost of doing re-establishment
        Not          fully aware of operating environment
    Flexibility in describing Service Level
     Objectives
        Not sure what to ask for (not fully aware of the
         environment in which operating)
        Too many violations


OGF21, October 2007                                           21
Dynamic WS-Agreement
    Case 1: Static Agreement
        IdentifyService Description Terms,
        Guarantee Terms, and
        Service Level Objectives (SLOs)
    Case 2: Dynamic Agreement
        IdentifyService Description Terms,
        Guarantee Terms: defined as ranges or as
         functions
        Service Level Objectives: defined as ranges
         or as functions

OGF21, October 2007                                    22
Conclusion
    WS-Agreement provides a useful basis for SLA
    Still restricted to “static” SLAs
        Does         not support negotiation mechanisms
    Negotiation should not be part of SLA
        SLA          should result as a consequence of negotiation
    Mechanisms for dynamic SLAs
        Function-based   or Category based (adaptation
            between categories)
    Dynamic SLA networks
        Means          to support dynamic SLA exchange networks


OGF21, October 2007                                                   23

								
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